Vacuum-pump.



G. F. NELSON.

VACUUM PUMP.

APPLICATION FILED NOV. 20,4915.

Patented Mar. 6, 1917.

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VACUUM PUMP.

APPLICATION FILED NOV- 20, 1915.

2 SHEETS--SHEET 2.

Patented Mar.

Inventom Georye Ell e-50m, 7 y M44406,

OFFICE.

GEORGE E. NELSON, or BERKELEY, CALIFORNIA.

VACUUM-PUMP.

To all whom it may concern: 7

Be it known that I, GEORGE. F. NELSON, a citizen of the United States, residing at Berkeley, in the county of Alameda and State of California, have invented new and useful Improvements in Vacuum-Pumps, of which the following is a specification.

The present invention relates to that class of vacuum pumps which depend upon the action of rotary coengaging gear wheels, and the object of the invention isto provide a pump which, first, will develop a higher degree of vacuum than those of this type heretofore employed, and, secondly, so con.- structed that the cost of manufacture shall be reduced to a minimum.

In the accompanying drawings, Figure 1 is a vertical section of my improved pump; Fig. 2 is a similar section taken at right angles to that shown in Fig. 1; Figs. 3, 4 and 5 are horizontal sections on the lines 33, 44 and 55 respectively of Fig. 1.

Referring to the drawing, 1 indicates an annular base having an inner raised portion 2 and a flange 3 around said raisedportion.

' Secured in said base adjacent to said flange are the lower ends of a number, preferably three, of rods 4, the upper ends of which are threaded, as shown at 6.- Seated upon said raised portion 2 of the base, within the flange 3, is the lower closed end of a cylindrical container 7 Within said container is a rotary gear-wheel pump 8 comprising a The lower reduced portion of said head comprises four radially extending portions, and,

at the bottom, an outwardly extending flange 15. Two diametrically opposite radially extending portions 16, 17 are for the purpose of holding shafts, and the other two 18, 19, are for the purpose of forming walls of conduits. The portion 16 is bored vertically to provide a bearing for a vertical operating shaft 21, the upper end of which carries a grooved ulley '22, by which said shaft can be rotated from any suitable source of power.

In the opposite radially extending portion Specification of Letters Patent. Application filed November 20, 1915. Serial No. 62,498.

' PatentedMar.B,191'7.

23. These shafts 2i and 23' extend in the pump to the same depth below the bottom of the flange 15.

To the bottom of said pump head is secured, by means to be presently described, a gear case 24 having a closed bottom 26 and an' open top, closed by the bottom of the pump head, which serves as a cover for the gear case. While I have in the present instance only shown one upper gear case, it is to be understood that they may be a series of any number of upper gear cases, all exactly alike, the bottom of each gear case serving in like inanner as the cover for the next lower gear case. In said gearcase are two intermeshing gear-wheels 27, 28, of which thewheel 27 is keyed, as shown at 29, on the shaft 21, while the other gear-wheel 28 is loose on the shaft 23. Immediately below the first gear case I have shown, in this case, the'lowermost gear case 31, there being shown only two gear cases altogether, althoughI- may use any number. In this case also there are a pair of gear-wheels 32,33, one 32 keyed to the shaft 21 and the other loose on the shaft 23. .All of these gear cases are secured to the pump head by means of screws 34, 36. Thehead of the screw 34 bears against the bottom of the lowermost gear case and said screw 36 extends through apertures in lugs 37 38 in the two gear cases and the top of the screw is screwed into a threaded socket in the radially extendlng portion 18. In like manner the head of the screw 34 bears against the under side of a lug 39, and the screw itself passes through apertures in said lug and in a lug 41 and said screw is screwed into a threaded socket in the opposite radially extending portions 19. By means of these two screws the gear cases and the pump head are held tightly together.

In said radially extending portion 18 there is formed a conduit 43 which leads radially inward and then in the top of the pump head downwardly into the middle pf one side of the cavity of the first gear case and into the inlet end of said conduit is screwed the inner end'of an outwardly tapering tube 44 upon the outer end ofwhich is slipped a rubber tube, not shown, which is connected.

other side of the gear case, opens through the bottom of the gear case and therefore communicates with the interior of the next succeeding gear case below it, since, as already stated, the bottom of each gear case forms a cover for the next succeeding gear case.

formed a channel 49 leading from the interior of the lower gear case and communicating with a hole 51 formed through the corresponding lug 41 of the upper gear case, which in turn communicates with the discharge conduit 46, leading, as heretofore stated, to the interior of the container.

Leading to the bearing for the rotating shaft 21 are lubricating conduits 52. Thereby not only is the bearing lubricated, but the oil forms a seal around the shaft preventing the leakage of air along said shaft to the first gear case.

Theforegoing being the construction of the apparatus, the following is the method of use. Oil is supplied to the receptacle until. it is at a level sufficiently above the lubricating conduits52. The shaft 21 being-now rotated, and supposing that the gear-wheels rotate in the direction of the arrow, as shown in Fig. 4, then, since the gear teeth move practically in contactfiwith theggear case, the oil inthe cavit between the sides of the gear-wheels fromw ich they rotate is carried by the teeth of said gear-wheel's away from the cavity on that side, and the outward motion of the oil therefore produces a suction of air which flows down from the chamber to be exhausted through the inlet conduit 43 and this air is carried with the oil around the gear-wheels to the opposite side thereof. This effect is produced at the same time by each pair of gear-wheels, so that the suction causes the air topass down into the transverse conduit 47 by said conduit to the lower gear case." When it.

i the teeth of the lowermost pair of'gearwheels where they mesh with each other, I provlde two small holes 56 in the bottom of thelowermost gear case, which admit oil, and since the container is at atmospheric pressure, and the interior of the lowermost gear'case is nearly at the pressure of the chamber which is being exhausted, the oil In the upper portion of the lug 39 is rushes in through these small holes, and is carried around by the teeth of the gearwheels until they mesh with each other, and this absolutely insures that no aircan pass from the discharge side of the pair of gear-wheels to the inlet side thereof. Furthermore it insures that there will be in the discharge conduit an almost continuous column of oil broken at intervals by columns of air, which latter columns become more and more minute as the pumping progresses, the air being discharged} from the top of the discharge conduit into the cylindrical container, from which it escapes to the atmosphere by a hole 57 through the pump head, the oil returning by gravity to the container.

wheels in' each gear case, a fixed shaft carried by the pump head and on which a geartary' shaft havin a bearing in the pump head and to Whic the other ar-wheel of veach pair is secured, each gear case having a transverse conduit leading from the space between the gear-wheels on one side of the gear case to the space between the gearwheels on the other side of the next lower gear case, the lowermost gear case having an entrance for liquid.- 7

2. The combination of a liquld contamer, a pump secured therein comprising "a pump 'head having exhaust and discharge conduits, a series of gear cases secured to said pump head, a pair of intermeshmg gearwheels in each gear case, a fixedshaft carried by the pump head and on which-a gearwheel .of each pair is loosely mounted, a rotary shaft having a bearing in the pump head and to which the other gear-wheel of each pair is secured, each gear case having wheel of each pair is'loosely mounted, a roa transverse conduit leading fromthe s ace between the gear wheels on one side 0 the gear case to the space betweenthe gearwheels on the other side of the next lower fgear case, the lowermost gear case having passages through its bottom for pumping up liquid, the pump head having an aperture therethrough for the escape of air from the container to the atmosphere.

3. The combination of a liquid container, pump secured therein comprising a-pump head having exhaust and discharge conduits,

a series of gear cases secured to said pump head, a pair of intermeshing gear-wheels in each gear case, a fixed shaft carried by'the pump head and on which a gear-wheel .of each pair ,is loosely mounted, a rotary shaft having a bearing in the pump head and to which the other gear-wheel of each pair is secured, each gear ease having a transverse condult leading from the space between thegear-wheels on one side of the gear case to the space between the gear wheels on the other sideof the next lower gear case, the lowermost gear case having a passage through its bottom for pumping up liquid,

the pump hea'd havinga lubricating conduit from the interior of the container to the bearing for the rotary shaft in the pump.

each gear case, a fixed shaft carried by the pump head and on which a gear-wheel of witnesses.

each pair is loosely mounted, a rotary shaft "having a bearing in the pump head and to 'WlHC-ll the othergea-r vheel of each pair is secured, each gene case having a transverse conduit leading from the spacebetween the gear-heels on one side of the gear case to'- the space between the gear-wheels on the} other side of the next lower gear case, thei lowermost gear case having a passage through its bottom'for pumping up liquid, the pump head havinga lubricating eonduit from the interior of the container to the bearing fol-the rotary shaft in the pump head, and also having an aperture therethrough for the escape of air from the coutainer to the atmosphere.

In testimonywhereof I have hereunto set my hand in the GEORGE F. NELSON. Witnesses: I I

- M. G. NELSON,

. G. F. NEIs0N,Jr.

.40 presence of two subscribing 

